The present invention relates to a fire-protection and safety composite glass panel having nonshattering property as well as fire resistant or fireproof property and, in particular, to such a glass panel comprising a fireproof glass plate and a fluorocarbon resin film of a chain molecular structure type laminated onto the glass plate for providing the nonshattering property.
In light of the recent expansion of large-sized buildings, such as department stores and supermarkets, the demand for such glass panels has increased. That is, to say a fireproof or fire-resistant property is required, such as a fire door, for blocking flame and smoke upon occurrence of fire. Thus to prevent the spread of fire, a nonshattering or shatter-resistant property is necessary for a safety glass plate for preventing damage or, shattering of cracked pieces to avoid generation of through holes therein.
For a fireproof glass plate to be used as a fire door, there has been available, for example, a wire glass plate or a heat-resistant transparent crystallized glass plate.
On the other hand, for a safety glass plate, there has been available, for example, a tempered glass plate, a laminated glass or a glass plate coated with a resin film.
The tempered glass plate is advantageous in that it is capable of resisting constant impact, and even if the plate is broken, the broken pieces are small enough to minimize the possibility of injury. On the other hand, it can be dangerous because the breaking of the glass plate can result in a through hole.
In view of this, the laminated glass plate or the resin-film coated glass plate having the nonshattering or shatter-resistant property is preferable to the tempered glass plate in that the demand for these nonshattering glass plates has been increasing as compared with the use of tempered glass plate.
A fire-protection and safety composite glass panel having both the fireproof property and the nonshattering property is disclosed in U.S. Pat. No. 5,230,954 (corresponding to JP-A-H04-224938 and JP-A-H05-70190) and has been provided for actual use.
The fire-protection and safety composite glass panel disclosed in the foregoing United States Patent is formed by bonding a fluorocarbon resin film of a chain molecular structure type onto at least one of opposite side surfaces of the heat-resistant transparent crystallized glass plate. The resultant composite glass panel has excellent characteristics in terms of the fireproof property and the nonshattering property. However, the manufacturing of such a composite glass panel presents a problem.
Specifically, the fluorocarbon resin film can be attached onto the glass plate using an adhesive or through thermo-compression bonding. With respect to using the adhesive, a material and a surface configuration of the adhesive should be strictly controlled such that it is laborious to assure quality control of the adhesive.
In case of the thermo-compression bonding, since a melting point of the fluorocarbon resin is higher than that of a polyvinyl butyral (PVB) resin or the like to be used for the normal laminated glass plate, a higher temperature is necessary for the bonding. Thus, special thermo-compression bonding equipments are required which increases the manufacturing cost of the fire-protection and safety composite glass panel.
In addition to the foregoing manufacturing problem, it is rather difficult to obtain the fluorocarbon resin of this type with high light transparency. Accordingly, if the fluorocarbon resin film of a large thickness is used, the resultant fire-protection and safety composite glass panel has slightly milky or opaline appearance and deteriorates in light transmittance.